Method of duplicating sound records



July 1941. K. DANIEL 2,247,991

METHOD OF DYUPLICATING souno RECORDS Filed June 21', 1938 Izgr] 1 I 9 9 e f lnvenzo/n- 7 Km, Mom,

Patented July 1, 1941 *M T OD.ornurtionmqsounnalso nuns 1:

Karl Daniel; Cologne-Sulz, Germany, assignor mf 11 Tefi-Apparatebau Dr. Daniel K.:,G., Cologne,

. Germany Animation-11. 9 221 rj a re- 1 9 In Germany June26,1937

v' eams'..,; (cud- 8.3)

This invention; relatesto amethodoiff'duplir eating sound records.

Band sound records produced by the needle sound recording method can be duplicated by preparing in a suitable manner, for instance by the electrogalvanic method, a matrix from the original recording and passing the matrix together with the band-like blank to be treated between two pressing rollers. This method involves, however, difliculties concerning the guiding of the matrix band, as it is hardly possible to produce a matrix band having perfectly smooth side edges and subsequent working of the latter, if possible at all, would be too expensive, because they must be adjusted to the sound tracks with absolute accuracy.

To overcome these troubles the invention proposes to provide the original sound record with grooves which extend parallel to the lateral edges and, by appearing on the matrix as ridges, permit a control thereof during the pressing operation. The ridges, which lie outside the range of the sound tracks, make possible mechanical guiding of the matrix band by means of a gauge.

Further, according to the invention, the matrix band is cut 011 or ground off along the lateral ridges, the cutting or grinding device itself being guided by the said ridges, so that the matrix band having smooth lateral edges on one or both sides can be easily guided.

By way of example, the invention is diagrammatically illustrated in the accompanying drawing, in which:

Figure 1 shows in elevation a section of a band sound record,

Figure 2 is a cross section thereof,

Figure 3 is a cross section of a matrix produced from the band sound record and of a guiding means, and

Figures 4 to 6 illustrate two diiferent pressing methods.

Referring to the drawing:

The film-like and band-shaped sound record a, which may be finite or endless, contains in the usual way a plurality of sound tracks b extending in longitudinal direction side by side. At both sides, near the sound tracks b, grooves c are cut into the sound record a. parallel to the lateral edges thereof, the cutting depth of the grooves being greater than that of the sound tracks I).

In the matrix 12 produced from the original sound record a and having jagged lateral edges the sound tracks appear in the form of elevations 6 and the grooves c as ridges or elevations f which are the counterparts ofthe grooves c. Fig. 3 shows how "a gauge 9 provided with indentations permits perfect guiding of the matrix d-.

As shown in Fig. 4, the matrix d together with the band It on which the copy is to be made is passed between two pressing rollers i and k, and in front of and behind the inlet of the matrix d between the rollers 1'. and k gauges o are provided for guiding purposes. The band h can be guided on its smooth lateral edges in the usual manner.

Figs. 5 and 6 illustrate another pressing method suited particularly for weaker matrices. The.

matrix d is spirally wound upon a roller 1. To ensure faultness winding the matrix band must be guided by the gauge g.

Fig. 6 shows how the band h passes between the rollers l and m, which necessitates, of course, axial displacement of the rollers l and m or a corresponding transverse displacement of the sound band h.

I claim:

1. In a method of duplicating sound records produced by the needle sound recording method, the steps of forming grooves on an original sound record carrier; preparing a matrix from said original, said matrix having ridges corresponding to said grooves; passing said matrix together with a blank, on which the sound records are to be reproduced, between two pressing rollers; and using said ridges to guide said matrix during the pressing operation.

2. In a method of duplicating sound records produced by the needle sound recording method, the steps of: cutting at least one groove into an original sound record, which extends parallel to the lateral edges of said record and lies outside the area of the sound tracks; preparing a matrix from said original sound record in which is provided a raised portion corresponding to said groove; and using said raised portion for guiding said matrix during the subsequent copying operation.

3. In a method of duplicating sound records produced by the needle sound recording method, the steps of forming grooves on an original sound record adjacent the sound tracks; preparing a matrix from said original, said matrix having ridges corresponding to said grooves; and utilizing said ridges for guiding said matrix during the subsequent copying operation.

4. In a method of duplicating sound records produced by the needle sound recording method, the steps of: preparing a matrix from an orignal sound record and forming ridges thereon during record strip having a plurality of sound tracks such preparation passing said matrix together with a blank film between two pressing rollers;

y and using said ridges for guiding said matrix during the pressing operation.

5. The method of producing sound records by 5 the needle sound recording method, which comprises preparing an original sound record strip having a longitudinal groove therein; preparing a matrix strip from said original record strip and having a ridge corresponding to said groove; and 10' preparing a sound record from said matrix, stripv by pressing a blank strip into forming contact therewith while employing said ridge. for .main-. U taining the alignment of said matrix and blank iP- 15 6. The method of producing sound records, which comprises preparing an original sound 1 extending along its length and also having a V p rtion o sss l f w se o Ot arted 20 neasur a t Qn t u H l n t d na g d marking-spaced froi'n'the sound tracks; prepar iatiogi "ing a matrix from said original record strip, said matrix having the counter-part of said sound tracks and of said oflset surface portion; and using said counter-part for determining the alignment of said matrix with a blank strip during the subsequent copying operation.

; 7. The method of producing sound records,

which comprises preparing an original sound record strip having a plurality of sound tracks extending along its length and also having a portion of its surface offset from other parts of the surface to constitute a longitudinal guide marking spaced from the sound tracks; preparing a matrix from said original record strip, said matrix having the counter-part of said sound tracks'and of v said offset surface portion; and pressing 'said matrix against a blank film strip for forming a duplicate of the sound tracks in said original record strip, while using said counterpart for determining the alignmentof said sound tracks relative to an edge of the blankstrip;

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